st: additional lines in a plot

[stef salvez <loggyedy@googlemail.com>]

Hi all,


 According to the dataset below i have observations every 28 days (4
weeks)  but in some cases i have jumps ( 35 days-or 5 weeks- and 42
days -or 6 weeks).

  I would like to construct vertical gridlines   every 28 days so as
to see easier the one- and/or two-week shifts. The solution mignt be
the
  -xaxis- command but i do not know exactly how to fit it to the code below


clear all
cd d:\
input str8  (Austria           Belgium          )
 "2/11/08"     "07/12/08"
"30/11/08"          "04/01/09"
"28/12/08"          "01/02/09"
"25/01/09"          "01/03/09"
"22/02/09"          "29/03/09"
"22/03/09"          "26/04/09"
"19/04/09"          "24/05/09"
"17/05/09"          "21/06/09"
"14/06/09"          "19/07/09"
"12/07/09"          "16/08/09"
"09/08/09"          "13/09/09"
"06/09/09"          "11/10/09"
"04/10/09"          "08/11/09"
"01/11/09"          "06/12/09"
"29/11/09"          "03/01/10"
"27/12/09"          "31/01/10"
"31/01/10"          "28/02/10"
"28/02/10"          "28/03/10"
"28/03/10"          "25/04/10"
"25/04/10"          "23/05/10"
"23/05/10"          "20/06/10"
"20/06/10"          "18/07/10"
"18/07/10"          "15/08/10"
"15/08/10"          "12/09/10"
"12/09/10"          "10/10/10"
"10/10/10"          "07/11/10"
"07/11/10"          "05/12/10"
"05/12/10"          "02/01/11"
"01/01/11"          "30/01/11"
"30/01/11"          "27/02/11"
"27/02/11"          "27/03/11"
"27/03/11"          "24/04/11"
"24/04/11"          "22/05/11"
"22/05/11"          "19/06/11"
"19/06/11"          "17/07/11"
"17/07/11"          "14/08/11"
"14/08/11"          "11/09/11"
"11/09/11"          "09/10/11"
"09/10/11"          "06/11/11"

end
gen dAustria = date(Austria, "DM20Y")
gen dBelgium = date(Belgium, "DM20Y")

gen dA2 = dAustria - dAustria[_n-1]
gen dB2 = dBelgium - dBelgium[_n-1]
 gen Aus= 10
gen Bel = 9
gen t10 = (dAustria + dAustria[_n-1]) / 2
gen t9 = (dBelgium + dBelgium[_n-1]) / 2

 scatter Aus  dAustria, xsize(20) ysize(8) c(l l)|| scatter Bel
dBelgium , c(l l)    || //
scatter Aus t10, ms(none) mla(dA2) mlabpos(910) || ///
scatter Bel t9 , ms(none) mla(dB2) mlabpos(910)
 yla(9 "Belgium"  10 "Austria"    , ang(h)) xla(, format(%td)) legend(off)

thanks
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